The invention relates to an improved fluid coupling and, more particularly, to an improved T coupling.
Fluid couplings have many uses. One of the more demanding uses is for surgical aspiration. The fluid flow paths including necessary couplings for surgical aspiration must avoid occlusion with tissue fragments and coagulating blood as well as kinking from the required movement of the surgical aspirator. Highly accurate flow rates prohibiting even partial occlusion are also required for aspiration of small body cavities such as the eye. Surgical couplings must also be easily and accurately assembled in an operating theatre and, preferably, sterile. Undesired, equipment damaging leakage flows must also be avoided.
Experience with surgical aspiration devices made by the assignee, Cavitron Corporation, has indicated a need to improve the fluid couplings on the devices and, particularly, a T coupling which provides pressure relief to the aspiration line on command. The pressure relief provides vital control of the extent of aspiration and releases the aspirator without pulling tissue if it attaches to a tissue surface with its suction. The variable height of the aspiration line relative to the aspiration unit as the aspirator is manipulated, however, can cause body liquids to enter the pressure relief line. A check valve was therefore provided in the relief line, but failures of the check valve which was small and delicate to be accommodated in the surgical-sized lines too frequently still allowed liquids into the relief line and damage to the equipment. Flow turbulance and protrusions at the coupling to the relief line also too frequently trapped aspirated tissue particles or coagulated blood, occluding the aspiration line at the coupling to the relief line, and requiring manual manipulation of the coupling to dislodge in a procedure nicknamed "flicking the T". Still further, the coupling arrangement and check valve, although small, held the aspiration line away from the device and thus encouraged aspiration-occluding kinking of the aspiration tube as it curved to the device for the application of the suction. Most importantly, however, the fittings for providing the necessary liquid and air fluid-tight couplings to the pressure relief line which were intended to slip together for easy use actually fit so tightly as to be difficult to use. This encourages operating room personnel to leave the check valve portion of the aspiration line on the aspiration device which, with the resulting accumulation of body salts in reuse, promoted failure of the check valve or, in the alternative, to use plyers in the operating theatre for assembling and disassembling the tubing. Experience with all of these problems clearly pointed to the need for an improved fluid T coupling for introducing the pressure relief fluid flow path to the aspiration fluid flow path.
A relatively new fluid coupling has a generally rigid base portion and an attached, relatively resilient face portion on a male member which is received in a generally cylindrical receptacle of a female member. The receptacle of the female member had an asymmetrical portion adjacent an opening into the receptacle so that the male member could be inserted and urged with a camming action upon rotation to compress the resilient face portion of the male member into fluid tight, sealing engagement with the receptacle with the least rotation of the male member in the receptacle. Fluid flow paths opening from the receptacle of the female member and the face portion of the male member were thus brought into sealed communication with a force diagonal of their junction. This fluid coupling therefore had promise for surgical use in providing a fluid coupling of just two, easily assembled components, but had not been used before for the more exacting requirements of a T coupling having both a through-flow path and a communicating, coupled path for both liquid and gas fluid communication as required for surgical aspiration pressure relief. An improved, T coupling embodiment was therefore required.